JP4621621B2 - Charged beam lithography system - Google Patents

Description

  The present invention relates to a charged beam drawing apparatus for drawing an LSI pattern using a charged beam, and more particularly to a charged beam drawing apparatus in which an electrostatic deflector is improved.

  In the electron beam drawing apparatus, various electrostatic deflectors such as a blanking deflector, a shaping deflector, and an objective deflector are used. The electrostatic deflector has a plurality of deflection electrodes, applies a potential generated by a deflection amplifier to each electrode, and deflects an electron beam by an electric field generated between the electrodes.

  One end of a coaxial cable is connected to the output end of the deflection amplifier, and the other end of the coaxial cable is connected to a deflection electrode of the electrostatic deflector. Usually, since the deflection electrode of the electrostatic deflector is electrically connected only to the coaxial cable, it is considered that a capacitive load is attached to the tip of the coaxial cable in terms of an equivalent circuit. For this reason, the signal input from the deflection amplifier is almost totally reflected by the deflection electrode, and the input signal returns to the deflection amplifier with a certain time delay corresponding to the length of the coaxial cable. In such a state, it is difficult to operate the deflection amplifier at high speed.

On the other hand, by connecting the deflection electrode to the ground side through a resistance equal to the characteristic impedance of the coaxial cable, it is possible to perform high-speed operation while suppressing the reflection of the signal at the deflection electrode (for example, Patent Documents). 1). However, in this case, since there is a current flowing through the resistor even when the voltage is constant, the load on the deflection amplifier becomes large and it is difficult to increase the drive voltage. For example, considering that 50Ω is used for the termination resistor and a voltage of 50V is applied, the termination resistor has a maximum current of 1A flowing at the maximum, which is a realistic burden on the amplifier, cable, and termination resistor. is not.
Japanese Patent Laid-Open No. 11-150055

  As described above, in the conventional electron beam drawing apparatus, it is difficult to realize the high-speed and high-voltage operation of the electrostatic deflector without increasing the load on the deflection amplifier. The above-mentioned problem can be similarly applied not only to the electron beam drawing apparatus but also to the ion beam drawing apparatus.

  The present invention has been made in consideration of the above circumstances, and the object of the present invention is to realize high-speed and high-voltage operation of an electrostatic deflector without causing an increase in load on the deflection amplifier. It is an object of the present invention to provide a charged beam drawing apparatus capable of improving the drawing speed.

  In order to solve the above problems, the present invention adopts the following configuration.

  That is, one embodiment of the present invention is a charged beam drawing apparatus that draws a pattern by irradiating a charged beam generated from a charged beam source to a desired position on a sample, and is downstream of the charged beam source. Is provided with an electrostatic deflector for deflecting a charged beam by an electric field, and the deflection electrode of the electrostatic deflector and the ground plane are insulated in a direct current manner, and the deflection electrode of the electrostatic deflector A capacitance and an electric resistance are arranged in series between the ground and the ground plane.

  Another embodiment of the present invention is a charged beam drawing in which a charged beam generated from a charged beam source is deflected by an electrostatic deflector and a pattern is drawn by irradiating the charged beam on a desired position on the sample. The electrostatic deflector includes a plurality of deflection electrodes arranged symmetrically with respect to the optical axis of the charged beam, and is arranged coaxially with the optical axis so as to surround the deflection electrode. A grounding outer cylinder provided; a resistance film provided on an inner surface of the grounding outer cylinder; and a conductive film provided on a surface of the resistance film, wherein a static electricity is provided between the deflection electrode and the conductive film. A capacitance is formed, and an electrical resistance is formed between the ground conductor and the conductive film.

  According to still another aspect of the present invention, charged beam drawing is performed by drawing a pattern by deflecting an electron beam generated from an electron gun by an electrostatic deflector and irradiating the sample with a desired position on the sample. The electrostatic deflector includes a plurality of deflection electrodes arranged symmetrically with respect to the optical axis of the electron beam, and is arranged coaxially with the optical axis so as to surround the deflection electrode. A grounding outer cylinder provided; a resistance film provided on an inner surface of the grounding outer cylinder so as to face the deflection electrode; a conductive film provided on a surface of the resistance film; and the conductive film; A high dielectric film inserted between the deflection electrode and mechanically supporting the deflection electrode, and an electrostatic capacitance is formed between the deflection electrode and the conductive film by the high dielectric film. Between the ground conductor and the conductive film Wherein the electrical resistance is formed by the resistance film.

  According to the present invention, by inserting an electrostatic capacitance and an electrical resistance in series between the deflection electrode and the ground plane or the outer shell, the electrostatic deflector can be operated at high speed without increasing the load on the deflection amplifier. High voltage operation can be realized, and thereby the drawing speed can be improved.

  The details of the present invention will be described below with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 is a schematic configuration diagram showing an electron beam drawing apparatus according to the first embodiment of the present invention.

  In the figure, 11 is an electron gun (charged beam source) that generates an electron beam, 12 and 13 are condenser lenses, 14 is a projection lens, 15 is a reduction lens, 16 is an objective lens, 21 is a first shaping aperture, and 22 is a first lens. 2 shaping apertures, 31 a blanking deflector for turning on and off the beam, 32 a shaping deflector for changing the size and shape of the beam, and 33 an objective deflector for scanning the beam on the sample surface , 41 indicates a sample such as a mask or a wafer, and 42 indicates a sample stage. Although not shown in the figure, the electron gun 11, the various lenses 12 to 16, the apertures 21 and 22, and the various deflectors 31 to 33 are accommodated in an electron optical column.

  The electron beam emitted from the electron gun 11 at the acceleration voltage of 50 kV is focused by the condenser lenses 12 and 13 excited so that the crossover image coincides with the deflection fixed point of the shaping deflector 32, and is focused on the first shaping aperture 21. Irradiated. The first shaping aperture 21 is provided with a rectangular opening, and the electron beam transmitted through the opening has a rectangular cross-sectional shape. The electron beam shaped into a rectangle by the first shaping aperture 21 is then focused by the projection lens 14 excited so that an image of the first shaping aperture 21 is formed on the second shaping aperture 22, and the second The molding aperture 22 is irradiated.

  Here, the beam irradiation position on the second shaping aperture 22 can be changed by the shaping deflector 32. Various shapes of openings are provided on the second shaping aperture 22, and an electron beam having a desired cross-sectional shape can be obtained by transmitting the beam to a desired position of the second shaping aperture 22.

  The electron beam that has passed through the second shaping aperture 22 is focused by the reduction lens 15 and the objective lens 16 and reaches the surface of the sample 41 placed on the stage 42. At this time, the electron beam is deflected by the objective deflector 33 and reaches a desired position on the sample 41.

  Here, as the deflectors 31, 32, and 33, electrostatic deflectors composed of a plurality of deflection electrodes are used. In these methods, a potential generated by a deflection amplifier is applied to a deflection electrode, and an electron beam is deflected by an electric field generated between the electrodes.

  2 and 3 are diagrams illustrating a specific configuration of the shaping deflector 32 used in the present embodiment. FIG. 2 is a cross section obtained by cutting the shaping deflector 32 perpendicular to the beam traveling direction, and FIG. 3 is a cross section obtained by cutting the shaping deflector 32 along the beam traveling direction. As an example, the number of deflection electrodes is four. Here, an example of the shaping deflector 32 will be described as an electrostatic deflector, but the objective deflector 33 can be similarly configured.

  The shaping deflector 32 includes four deflection electrodes 51 (51a, 51b, 51c, 51d). That is, the deflection electrodes 51a and 51c are arranged opposite to each other with the beam axis interposed therebetween, and a deflection voltage in the x direction, for example, is applied between these deflection electrodes. The deflection electrodes 51b and 51d are arranged opposite to each other with the beam axis interposed therebetween, and a deflection voltage in the y direction, for example, is applied between these deflection electrodes.

  Four deflection electrodes 51 are arranged concentrically in a grounded outer cylinder 52 arranged coaxially with the optical axis. Each deflection electrode 51 is formed of a plate and is curved along a concentric circle centered on the beam axis. That is, the cross section in the direction orthogonal to the beam axis is formed in an arc shape. The portions of the deflection electrode 51 that are adjacent to each other are thinned, thereby reducing the capacitance between the adjacent deflection electrodes. Resistors 53 (53a, 53b, 53c, 53d) are respectively disposed between the respective deflection electrodes 51 and the grounded outer cylinder 52. The resistor 53 is, for example, a silicon carbide film.

  The deflection amplifier 54 is connected to each of the four deflection electrodes 51 by a coaxial cable 55. FIG. 2 shows only one connection and FIG. 3 shows only two connections. The description will be made assuming that the characteristic impedance Zc of the coaxial cable 55 is 50Ω. It is also possible to use a cable with a value of 75Ω or higher as Zc. This figure is schematic and does not reproduce the actual structure and dimensions.

  The shaping deflector 32 includes a deflection electrode 51, a space, a resistor 53, and a grounding outer cylinder 52 from the inside. Therefore, an electrostatic capacity and an electric resistance are connected in series between the deflection electrode 51 and the grounded outer cylinder 53, and an equivalent circuit is as shown in FIG.

  The resistors 53 are desirably divided by the number of the deflection electrodes 51. However, when the deterioration of the characteristics can be allowed, an integrated structure may be used as shown in FIG. The deflection electrode 51 and the resistor 53 are electrically insulated. In order to maintain this insulation structure, the insulation body 53 is actually insulated from the resistor 53 with an insulator sufficiently smaller than the electrode structure. Strictly speaking, the resistance value between the deflection electrode 51 and the resistor 53 is finite even when they are connected by an insulator. However, if the value is sufficiently larger than the resistance of the resistor 53, it can be regarded as an insulator. For example, 1 MΩ or more is usually sufficient. Although omitted in FIG. 2, an insulator 56 for mechanically holding the deflection electrode 51 is provided in a part between the resistor 53 and the deflection electrode 51. The inner surface of the resistor 53 is coated with a good conductor 57 such as copper.

In this structure, the resistance value R between the grounding outer cylinder 52 and the inner conductor 57 of the resistor 53 is set to a value substantially equal to the characteristic impedance Zc of the coaxial cable 55. In this example, it is determined to be 50Ω. The length L in the optical axis direction of the deflection electrode 51 is 120 mm, and the outer diameter 2r of the cylinder formed of the four deflection electrodes is 20 mm. Further, the distance between the deflection electrode 51 and the inner conductor surface of the resistor 53 is set to 0.6 mm. The capacitance C in this case is approximately C to ε0 × 2π × r × L / 4d to 28 pF when the dielectric constant in vacuum is ε0.
It becomes. This value is sufficiently larger than the interelectrode capacitance between adjacent deflection electrodes.

  At this time, if the resistance value R between the inner conductor 57 of the resistor 53 and the grounded outer cylinder 52 is 50Ω, the time constant when viewed from the outside of the deflection electrode 51 is about 1.4 ns. The time constant of 1.4 ns is shorter than the beam stabilization time of a normal deflection amplifier, and therefore there is no response delay due to this time constant. Since the insulator 56 between the resistor 53 and the deflection electrode 51 works to increase the capacitance, the outer diameter of the deflection electrode 51 is actually made slightly smaller so that the capacitance does not become larger than the above value. It is desirable.

If silicon carbide having a resistivity of 10 ⁵ Ωcm is used as the resistor 53, if the inner diameter is 21.2 mm and the thickness is 2 mm, the resistance value in the direction perpendicular to the beam axis may be approximately 50 Ω. it can. The resistor 53 is fixed in close contact with the grounding outer cylinder 52 so as to make the contact resistance as small as possible. In order to apply a voltage to the deflection electrode 51, appropriate holes are formed in the grounding outer cylinder 52 and the resistor 53, and the core wire of the coaxial cable 55 and the deflection electrode 51 are connected through the hole. If the thickness of the end portion in the circumferential angle direction of the deflection electrode 51 is 1 mm, the mutual capacitance between the adjacent electrodes is about 1 pF when the interval between the adjacent electrodes is 1 mm. The capacitance between the resistor 53 and the resistor 53 can be made sufficiently smaller.

  FIG. 6 is a diagram conceptually showing the electrical characteristics of the shaping deflector 32 when configured as described above. As shown in FIG. 6A, in a relatively low frequency region, for example, 1 MHz, the absolute value of the complex impedance ZL of the shaping deflector 32 is | −i / (Cω) + R | = 5.7 kΩ and a sine with an amplitude of 50V. The current is suppressed to about 10 mA in amplitude with respect to the wave voltage. On the other hand, as shown in FIG. 6B, in a relatively high frequency region, for example, 1 GHz, it is almost 50Ω, and the voltage reflectivity at the shaping deflector 32 is as small as 0.06 or less. That is, it is possible to make almost no reflection in the high frequency region. Assuming that the time constant is 1.4 ns, the time from 0 volt to (1-110,000) V volt is about 13 ns with respect to the step input from 0 volt to V volt. That is, the voltage can rise very quickly.

  As described above, according to the present embodiment, the deflection electrode 51 of the shaping deflector 32 is connected to the grounded outer cylinder 52 via the electric resistance and capacitance formed of the resistor 53, and the resistance value of the resistor 53 is deflected. By making the value approximately equal to the characteristic impedance of the coaxial cable 55 connected to apply a voltage to the electrode 51, impedance matching can be achieved in the high frequency region while maintaining a state in which the direct current is insulated from the ground plane. Signal reflection can be suppressed by approaching the state. As a result, the influence of the reflected wave is reduced in the high frequency region for the deflection amplifier 54 that drives the shaping deflector 32, and the shaping deflector 32 can be operated at a high speed and a high voltage. That is, it is possible to realize a high-speed and high-voltage operation of the shaping deflector 32 without causing an increase in load on the deflection amplifier 54, thereby making it possible to improve the drawing speed.

(Second Embodiment)
FIG. 7 is a view showing an example of a shaping deflector used in an electron beam drawing apparatus according to the second embodiment of the present invention. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  This embodiment is different from the first embodiment described above in that a high dielectric 71 (71a to 71d) that is an insulator is provided between each deflection electrode 51 and the resistor 53 of the shaping deflector 32. It is in having inserted. As the high dielectric 71, for example, alumina can be used. Strictly speaking, although the resistance of the high dielectric is finite, it can be regarded as an insulator because the resistance is sufficiently larger than the resistance of the resistor 53. By providing the high dielectric 71, the capacitance can be increased if the resistor 53 and the deflection electrode 51 are the same distance, and the distance between the resistor 53 and the deflection electrode 51 can be increased if the capacitance is the same.

  With such a configuration, the same effect as that of the first embodiment can be obtained, and the distance between the deflection electrode 51 and the resistor 53 can be made wider than the example of FIG. Therefore, there is an advantage that machining and assembly are easy.

(Third embodiment)
FIG. 8 is a diagram showing an example of a shaping deflector used in an electron beam drawing apparatus according to the third embodiment of the present invention. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  This embodiment is different from the first embodiment described above in that a dielectric 81 (81a to 81d) is inserted between each deflection electrode 51 of the shaping deflector 32 and the resistor 53, and further a dielectric. 81 and the resistor 53 are not formed in a plate shape but in an integrated rod shape (cuboid). The resistor 53 and the dielectric 81 integrally support the deflection electrode 51.

  Also in this embodiment, the material and shape are determined so that the resistance value R of the resistor 53 is 50Ω. For example, if the cross-section is a square with a side of 2 cm and a hole with a square hole with a side of 1 cm inside, and the resistivity is 100 Ωcm, the required length of the resistor 53 is 1 .5cm. Then, the deflection electrode 51 can be fixed to the grounding outer cylinder 52 through a screw formed of an insulating material in a hole of the rectangular parallelepiped material and the dielectric material.

  With such a configuration, the same effect as in the first embodiment can be obtained, and the deflection electrode 51 is screwed to the grounding outer cylinder 52 through the holes of the dielectric 81 and the resistor 53. Therefore, there is an advantage that machining and assembly are further facilitated.

(Modification)
The present invention is not limited to the above-described embodiments. In the embodiment, the deflection electrode has a shape along an arc centered on the beam axis. However, the deflection electrode does not necessarily have an arc shape, and may be a flat electrode. Further, the number of deflection electrodes is not limited to four, and may be two or eight deflection electrodes.

  In the present embodiment, the grounding outer cylinder is provided in the optical barrel, but the grounding outer cylinder may be omitted. In this case, the electron optical column itself may be used as the ground plane. In the embodiments, the electron beam drawing apparatus has been described as an example. However, it is needless to say that the present invention can be similarly applied to an ion beam drawing apparatus that electrostatically deflects a beam. In addition, various modifications can be made without departing from the scope of the present invention.

1 is a schematic configuration diagram showing an electron beam drawing apparatus according to a first embodiment. Sectional drawing which cut | disconnects and shows the shaping | molding deflector used for 1st Embodiment in the direction orthogonal to an optical axis direction. Sectional drawing which cut | disconnects and shows the shaping | molding deflector used for 1st Embodiment along an optical axis direction. The equivalent circuit diagram which shows the connection state of the deflector and deflection | deviation amplifier of 1st Embodiment. Sectional drawing which shows the modification of 1st Embodiment. The schematic diagram for demonstrating the change of the impedance in a low frequency area | region and a high frequency area | region for demonstrating the effect | action of 1st Embodiment. Sectional drawing which cut | disconnects and shows the shaping | molding deflector used for 2nd Embodiment in the direction orthogonal to an optical axis direction. Sectional drawing which cut | disconnects and shows the shaping | molding deflector used for 3rd Embodiment in the direction orthogonal to an optical axis direction.

Explanation of symbols

11 ... electron gun (charged beam source)
DESCRIPTION OF SYMBOLS 12, 13 ... Condenser lens 14 ... Projection lens 15 ... Reduction lens 15 ... Objective lens 21 ... 1st shaping | molding aperture 22 ... 2nd shaping | molding aperture 31 ... Blanking deflector 32 ... Molding deflector 33 ... Objective deflector 41 ... Sample 42 ... Stage 51 (51a to 51d) ... Deflection electrode 52 ... Grounding outer cylinder 53 (53a to 53d) ... Resistor 54 ... Deflection amplifier 55 ... Coaxial cable 56 ... Insulator 57 ... Internal conductor 71 (71a to 71d) ... High dielectric Body 81 (81a-81d) ... dielectric

Claims (7)

A charged beam drawing apparatus for drawing a pattern by irradiating a desired position on a sample with a charged beam generated from a charged beam source,
An electrostatic deflector for deflecting the charged beam by an electric field is provided downstream of the charged beam source, and the deflection electrode of the electrostatic deflector and the ground plane are insulated in a direct current manner. A charged beam drawing apparatus, wherein a capacitance and an electric resistance are arranged in series between a deflection electrode of the electrostatic deflector and a ground plane. A charged beam drawing apparatus for drawing a pattern by deflecting a charged beam generated from a charged beam source by an electrostatic deflector and irradiating the charged beam on a desired position on a sample,
The electrostatic deflector includes a plurality of deflecting electrodes arranged symmetrically with respect to the optical axis of the charged beam, and a grounding device disposed coaxially with the optical axis so as to surround the deflecting electrode. A tube, a resistance film provided on the inner surface of the grounded outer cylinder, and a conductive film provided on the surface of the resistance film,
A charged beam drawing apparatus, wherein a capacitance is formed between the deflection electrode and the conductive film, and an electric resistance composed of the resistance film is formed between the ground conductor and the conductive film.   A high dielectric is disposed in a portion where the electrostatic capacitance is to be formed between the deflection electrode and a ground plane or a grounding outer cylinder, and the dielectric mechanically supports the deflection electrode. The charged beam drawing apparatus according to claim 1, wherein A charged beam drawing apparatus for drawing a pattern by deflecting an electron beam generated from an electron gun by an electrostatic deflector and irradiating the electron beam to a desired position on a sample,
The electrostatic deflector includes a plurality of deflection electrodes arranged symmetrically with respect to the optical axis of the electron beam, and an external ground provided coaxially with the optical axis and surrounding the deflection electrode. A tube, a resistance film provided on the inner surface of the grounding outer cylinder so as to face the deflection electrode, a conductive film provided on the surface of the resistance film, and the conductive film and the deflection electrode. Each having a high dielectric film inserted between them and mechanically supporting the deflection electrode,
A charged beam in which an electrostatic capacitance is formed by the high dielectric film between the deflection electrode and the conductive film, and an electric resistance is formed by the resistive film between the ground conductor and the conductive film. Drawing device.   5. A time constant determined by a product of the capacitance and electric resistance is shorter than a settling time of a deflection amplifier for applying an electric field to the electrostatic deflector. Charged beam lithography system.   5. The electrostatic deflector is connected to an output end of a deflection amplifier via a coaxial cable, and the electric resistance is substantially equal to a characteristic impedance of the coaxial cable. Charged beam lithography system.   5. The charged beam drawing according to claim 1, wherein a capacitance between the deflection electrode and a ground plane or a grounding outer cylinder is larger than a capacitance between adjacent deflection electrodes. apparatus.

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